Fuel flow control device



Oct. 20, 1959 R. B. MATTHEWS 2,909,218

FUEL FLOW CONTROL DEVICE Filed April 23, 1956 2 Sheets-Sheet 1 FIG.I.

4 a? I 35 I 17 I8 I0 I I I4 5 I 23 a 16 I l3 8 5 I02 I I03 29 I I 27 I II 66 64 65 n |27 I l I INVENTOR. RUSSELL B. MATTHEWS 0a. 20, 1959 R. B.MATTHEWS 2,909,218

FUEL FLOW CONTROL DEVICE Filed April 23. 1956 2 Sheets-Sheet 2 INVENTOR.RUSSELL B. MATTHEWS ATTORNEYS United Statesv Patent FUEL FLOW CONTROLDEVICE Russell B. Matthews, wauwatosa, Wis., assignor to Baso Inc.,Milwaukee, Wis., a corporation of Wisconsin Application April 23, 1956,Serial No. 579,851

17 Claims. (31. 158123): a

This invention relates to improvements in fuel flow control devices, andmore particularly to thermoelectrically powered high-low fuel controlvalves. Experience has shown that modulation of theheat supplied to agiven'space from fluid fuelburning heating" apparatus in accordance withthe heat loss fromsaid space can be efiectively provided by flow controldevices which are operable to permit fuel flow to said apparatus ateither a high or a low rate depending upon the temperature Within saidspace, and which are operable .toshut off all fuel flow to the apparatuswhen the temperature within the space reaches a predetermined level." Incontrol devices of this type, the low rate of flow permitted there'- bymust not be less than the minimum at which .the bulner can safely burnthe fuel, and it is also necessary that for safe initial ignition of thefuel at the burner the high rate of flow be delivered thereto, the lowrate, of

course, being unsafe for such ignition purposes.

While it is desirable to provide the aforementioned high-low type ofcontrol in a system which is self powered, i.e. a system which ispowered by current derived, for

example, from a thermoelectric generator subject to? the heat of burningfuel at a pilot burner, the work required to actuate a main fuel valveto open positionagainstv the line pressure takes sucha large percentageof the power available from the thermoelectric generator when. such avalve is actuated by a direct acting operator, that the thermostat leadsmust be kept relatively short in order to maintain the circuitresistance sufiiciently low to permit thermoelectric current to bedelivered to the operator in sufficient quantities for actuation of themain fuel valve.

With the above in mind, it is a general. object of the present inventionto provide an improved high-low fuel' flow control device having a highcapacity valve operable when open to permit delivery of fuel to the mainburner at a relatively high rate, and having a low capacity fuel valveoperable when open to permit fuel flow to'the main burner at arelatively low rate, there being fluid pressure operated actuating meansfor said .main valve and a thermoelectrically powered operator having apair of armatures, one for actuating the low capacity fuel valve, andthe other for actuating pilot valve meansffor said fluid pressureoperated actuating means, actuation of said low capacity fuel valve andof said pilot valvemeans requiring only a relatively small amount ofpower, thus permitting remote location of the thermostat controllingsaid control device.

Another object of the invention is to provide an improved fuel controldevice of the aforementioned character wherein the electromagneticoperator has a pair of energizing windings and is so constructed thatenergization of both of said windings is required to effect armatureactuation, said energization effecting actuation of both of saidarmatures to attracted position and thereby opening of both the high andlow capacity valves to thereby inherently afford a high rate of fuelflow tothemain burner for safe initiation of ignition of the" fuelthereat, subsequent deenergization of-one of said coils'etrecting' drop2,909,218 Patented Oct. 20, 1959 out of one of the armatures and closureof the high capacity fuel valve to permit fuel flow to the main burnerthrough said low capacity fuel valve at the relatively low rate which isat least sufficient to afford safe burning of the fuel at the mainburner.

Another object of the invention isto provide an improved fuel controldevice of the class described, the operator of which includes anelectromagnet frame having a separate pair of pole pieces cooperablewith each of the armatures, energization of the first winding aifordingflux flow through said first armature and the pole pieces cooperabletherewith to provide attractive force sufficient to hold said firstarmature in attracted position when moved thereto against the bias,energization of the second winding while the first armature is inattracted position affording with the flux from the first winding a fluxdensity more than suflicient to saturate a portion of said frame,wherefore flux is shunted from said saturated portion through the otherpair of pole pieces to link the second armature and actuate the latterto attracted position against a bias.

Still another object of the invention is to provide an improved fuelcontrol device of the aforementioned character wherein both of theenergizing windings are connected for energization by athermoelectricgenerator, energization of each of said windings being under the controlof a separate thermostat contact.

Still another object of the invention is to provide an improved fuelcontrol device of the class described wherein there is pressureregulating means operatively connected to the high capacity fuel valvefor movement therewith and operable to maintain the pressure of the fueldelivered to the main burner within predetermined limits had to theaccompanying drawings illustrating one complete embodiment of theinvention and wherein like characters of reference indicate the sameparts in all of the views. In the drawings:

Figure l is a vertical sectional View taken through the improved controldevice with the fuel connections thereto shown diagrammatically; and

Figure 2 is a diagrammatic view showing the electrical system of theimproved control device including a two stage thermostat, parts of whichare broken away in section.

Referring more particularly to Figure 1 of the drawing, the illustratedform of the improved control device comprises a control body 4 which maybe made up of superimposed body parts 5, 6 and 7, the body part 5 beingformed with an inlet chamber 8 for receiving a fuel supply conduit 9 andalso being formed with a fuel outlet chamber 10 from which fuel'may bedelivered, for example through a conduit 11, to a main burner 12. Thebody part 5 is formed with a partition 13 separating the inlet chamber 8from the outlet chamber 10 and formed with an annular valve seat 14 for,cooperation with a relatively high capacity fuel valve member 15. Thepartition 13 may also be formed with a tapered or conical surface 16 fora purpose to be more fully described hereinafter. The body part6 isformed with a recess 17a, and a diaphragm 18, which is marginallyclamped by the body. par-ts 5 and 6 forms a chamber 17 with said recess.A seal between the body parts 5 and 6 is effected by means of a gasket19. The diaphragm 18 is centrally clamped between the valve member 15and a back-up plate 20, and the valve member 15 may be biased towardseated engagement with respect to the seat 14 by means of a compressionspring 21. The spring 21 may be deleted if desired.

The body part 6 is formed with a passageway 22 therethrough whichcommunicates at its lower end with a branch passage 23 formed in thebody part and intersecting the inlet chamber 8 as shown. The body part 6is formed with an annular valve seat 24, and a relatively small capacityfuel valve 25 cooperates with said seat to control the flow of fuel fromthe passageway 22 into a passage 26. A conduit 27 affords communicationbetween the passage 26 and a passage 28 formed in the body part 5 incommunication with the outlet chamber as shown. A metering screw 29 maybe provided for adjusting the amount of fuel which can flow into theoutlet chamber 10 through the passage 28. The small capacity valvemember is carried by a spiral biasing spring 30 which biases said valvemember toward the seat 24, said spring also carrying a magnetic memberor magnetically permeable armature 31.

The body part 6 is also formed with a recess 32 formed with an annularvalve seat 33 surrounding a bleed port or passage 34 which maycommunicate with a bleed conduit 35 extending to a position adjacent themain burner 12 as shown. A bleed port valve 36 cooperates with the seat33 and is carried by a spiral spring 37 which biases said valve towardsaid seat. Also carried by the spiral spring 37 is a magnetic member ormagnetically permeable armature 38. A passage 39 affords communicationbetween the recess 32 and the chamber 17 as shown.

The body part 7 is provided with a cover member 40 having a centrallydisposed depending lug 41. A magnetic member or magnetically permeableelectromagnet frame 42 shown most clearly in Figure 2, is generallyH-shaped in plan view and has a cross bar portion formed with anaperture 43 separating portions of reduced cross section 105 and 106. Asshown in Figure 1, the depending lug 41 projects through the aperture 43in the frame 42, and said frame is held in abutting relation with theunderside of the cover member 40 by means of a friction clip 44 whichengages both the lug 41 and the portions 105 and 106 of said frame.

As shown in Figure 2, each of the arms of the electromagnet frame 42 isprovided with a depending leg or pole piece, said legs or pole piecesbeing indicated by the numerals 45, 46, 47 and 48. The body part 7 issealingly connected to the body part 6, as by a gasket 49, and the bodypart 7 is formed with a partition 50 defining a recess 51 which with therecess 32 forms a chamber 52. The partition 50 is formed with a pair ofslots (not shown) through which the depending legs 47 and 48 oftheelectromagnet frame 42 project into the chamber 52. A sealing gasket53, for example of rubber, is disposed within the recess 51 and isformed with slots (not shown) to snugly receive the depending legs 47and 48, and a clamping plate 54 of non-magnetic material is alsodisposed within the recess 51 and is formed with slots (not shown) toreceive the depending legs 47 and 48. The clamping plate 54 is staked inoperative position clamping the sealing gasket 53 between said plate andthe partition 50 to form a gas tight seal around the legs 47 and 48.

The partition 50 is also formed with an opening 55 intermediate the legs47 and 48, and the gasket 53 is formed with a coaxial tapered opening 56while the clamping plate 54 is also formed with a coaxial opening 57.Pilot valve means or a frusto-conical valve member 58 is movable intoand out of seating engagement with the tapered opening 56 and isprovided with a stem portion 59 extending loosely through the aperture55 and having a connection with one end of a leaf spring 60, the otherend of said spring being anchored to the partition 50 as by a screw 61.The leaf spring 60 biases the valve member 58 downwardly toward flowpermitting position with re-, spect to the opening 56 and also tends tobias the lower end of the stem 59 into engagement with the armature 38as shown. 7

The lower ends of the electromagnet frame legs 45 and 46 terminate incoplanar pole faces, and the lower ends of the legs 47 and 48 alsoterminate in coplanar pole faces. The armature 31 is movable from theretracted position shown in Figure 1 to an attracted position inengagement with the pole faces of the frame legs 45 and 46. Similarly,the armature 38 is movable from the retracted position shown intoengagement with the pole faces of the frame legs 47 and 48. As thearmature 38 moves toward attracted position, such movement effectsseating of the valve member 58 within the opening 56, and simultaneouslylifts the bleed port valve 36 off the annular seat 33.

An energizing winding 62 is wound on the frame leg 45, and an energizingwinding 63 is wound on the frame leg 46. A thermoelectric generator 64,which may take the form of a thermocouple, is disposed with its hotjunction or junctions subject to the heat of burning fuel at a pilotburner 65 which is mounted in coacting relation with the .main burner 12as shown in Figure 1. One terminal of the generator 64 may be groundedas shown, and the other terminal of said generator is connected, as by aconductor 66 to one end of each the windings 62 and 63. The other end ofthe winding 62 is connected to an insulated contact 67 of a two stagethermostat 68, by a conductor 69, and the other end of the winding 63 isconnected to an insulated contact 70 of said thermostat by a conductor71.

While the two stage thermostat 68 may take a variety of forms, theillustrated form is believed to be preferable. The thermostat 68comprises a frame having side walls 72 and 73 and an end wall 74, thelatter having one end of each of a pair of expansible and contractiblehermetically sealed metallic bellows 75 and 76 fixed thereto. Thecontact 67 sealingly and fixedly extends through the end wall of thebellows 75 and adjacent the frame wall 74, and the opposite end wall ofsaid bellows carries a contact 77 which is movable toward and away fromcircuit-making engagement with the contact 67 on expansion andcontraction of the bellows 75. Similarly, the contact 70 sealingly andfixedly extends through the end Wall of the bellows 76 adjacent theframe end wall 74, and the opposite end wall of said bellows carries acontact 78 which is movable toward and away from circuit-makingengagement with the contact 70 on expansion and contraction of thebellows 76. The thermoelectric circuits between the coils 62 and 63 andthe grounded terminal of the thermoelectric generator is completed bygrounding of the thermostat frame, as through a conductor 97.

A capillary tube 79 has branches 80 and 81 communicating with theinteriors of the bellows 75 and 76 respectively, and the free end ofsaid tube terminates in a temperature sensing bulb 82 for sensingtemperatures remote from said bellows. The contacts of the thermostat 68are of low resistance, and the bulb 82, tube 79 and the bellows 75 and76 preferably contain a temperature responsive expansible andcontractible volatile fluid fill of a character which will notdeleteriously effect the low resistance character of the contacts withinsaid bellows.

Means is provided for supplying a contractile bias to the bellows 75 and76 and for selectively adjusting the control points of the contactstherein simultaneously. The aforementioned means may take the form of agenerally U-shaped yoke 83 which is slidable longitudinally of thebellows, for example between guides 84 projecting inwardly from theframe side Walls 72 and 73. The yoke 83 carries a stem or plunger member85 which is slidable in a bearing member 86 and engages a cam 87 carriedby a shaft 88 which may be provided with a manually engageable knob (notshown). A compression spring 89 has one end abutting the inner end wallof the bellows 75 and has its opposite end received by a retainer plate90 carried by a factory adjustment screw B 91 threaded through asuitable aperture in' the yoke 83 andprovided with lock nuts 92 forlocking the screw 91 in a selected position. A compression spring 931hasone end thereof abutting the inner end wall of the bellows 76 and hasits opposite end receivedby a retainer plate 94 carried by a factoryadjustment screw 95 which is threaded through a suitable aperture in theyoke 83 and is provided with lock nuts 96 for locking the screw 95 in aselected position of adjustment. It will be observed that the bias ofsprings 89 and 93 exert forces tending tocompress the bellows 75 and 76and tending to move the yoke 83 toward the right as viewed in Figure 2to thereby maintain the plunger 85in engagement with the cam 87. It willalso be observed that by rotation of the cam 87, the amount of biasexerted on both of the bellows 75 and 76 can be adjusted simultaneouslythereby adjusting both of the control points of said thermostatsimultaneously. The differential between the control points of thecontacts 77 and 78 can be adjusted by adjustment of the screws 91 and95, it being preferred to have the control point of the contact 77 setsomewhat higher, for example 3 F., than that of the contact 78.

Where regulation of the pressure of the fuel to the main burner 12 isdesired, the improved control device may be provided With means thereforwhich will now be described. Fixed to and depending from the highcapacity valve member 15 is a stem member 98 which carries afrusto-conical flow limiting member 99. The stem member 98 carries atits lower end a U-shaped bracket 100 having outturned ear portions.Cooperable with the bracket 100 is a generally U-shaped bracket 101having inturned ear portions overlapping those of the bracket 100 asshown. A spring 102, extending within a suitable passage 103, formed inthe body portion 5, has one end anchored to the bracket 101 and has itsopposite end anchored to a set screw 104 threaded into the passage 103as shown.

' The arrangement of the parts of the pressure regulating means is suchthat when the high capacity valve member 15 is raised to its normal openposition, the member 99 and bracket 100 are lifted therewith to move theoutturned ears of the bracket 100 into engagement with the inturned earsof the bracket 101. In this position the flow restricting member 99exerts no substantial restriction upon the flow of fuel past the seat14. If, however, the pressure of the fuel supplied to the conduit 9 isincreased to a value above normal, the effect of this increased pressureon the underside of the diaphragm 18 tends to lift the valve member 15farther, whereupon the flow restricting member 99 is raised against thebias of the spring 102 acting through the brackets 100 and 101. Suchfurther movement of the member 99 restricts the amount of fuel which canflow past the valve seat 14 and thereby reduces the pressure of the fuelin the outlet so that said pressure is maintained within predeterminedlimits in spite of substantial fluctuations in the pressure of the fuelin the inlet chamber 8.

The operation of the improved control device will now be described. Theparts of the improved control device are disposed as shown in Figure 1when the thermostat 68 is not calling for heat, the temperature sensedby the bulb 82 at such a time being sufliciently high so that expansionofthe fluid fill in the bellows 75 and 76 has moved the contacts 77 and78 to circuit-interrupting position for deenergization of the windings62 and 63. The small capacity valve 25 being seated on the seat 24,prevents fuel flow to the main burner past said seat. Disposition of thearmature 38 in the position shown in Figure 1 effects closure of thebleed valve36 and permits the leaf spring 60 to open the valve member58. This permits fuel to flow from the inlet chamber 8 through thepassages 23 and 22 and through the passage 55 in the partition 50, intothe chamber 52, to pressurize said chamber and, through the passage 39,to pressurizethe chamber 17 above the diaphragm 18. Pressurizing of thechamber 17 with line pressure effects closure of the valve member 15.Since both the small capacity valve 25 and the large capacity valve 15are closed, no fuel can flow to the main burner 12.

As the temperatures sensed by the bulb 82 drops to the control point ofthe contact 77, engagement of the contact with the contact 67 completesthe circuit between the generator 64 and the winding 62 for energization.of the latter. This causes generation of flux which flows through amagnetic'path including the leg 45, the cross bar portions and .106, andthe leg 46, and links the armature 31. The flux generated byenergization of the winding 62 is, however, insuflicient to elfectpull-in of the armature 31 against the bias of the spring 30.

As the temperature sensed by the bulb 82 continues to drop and reachesthe control point of the contact 78, the latter engages the contact 70to complete the energizing circuit between the generator 64 and thewinding 63 for energization of the latter. The energized winding 63generates a flux which flows in the same direction as that generated bythe winding 62, and the combined flux is sufficient to effect pull-in ofthe armature 31 and opening of the small capacity valve 25. As thearmature 31 pulls in, the reluctance of the aforementioned magnetic pathis reduced, and the combined flux is greater in magnitude than thatwhich can be accommodated by the reduced cross section portions 105 and106. As a result, the portions 105 and 106 become saturated, and theexcess flux flows through the depending legs 47 and 48 to link thearmature 38 and effect pull-in thereof against the bias of the springs37 and 60. Pull-in of the armatures 31 and 38 is substantiallysimultaneous, though sequential.

Pull-in of the armature 38 closes the valve 58 and unseats the bleedport valve 36 to bleed the chamber 17 to the atmosphere through thepassages 39 and 34. The line pressure acting on the underside of thelarge capacity valve 15 is now sufficient to lift said valve against thebias of the spring 21 to permit fuel flow to the main burner 12 pastboth the high and the low capacity valves, thus supplying a relativelylarge volume of fuel to said main burner insuring safe ignition of saidfuel by the pilot burner 65.

As the temperature sensed by the bulb 82 increases as a result of a highflame at the main burner and reaches the control point of the contact78, said contact moves to circuit-interrupting position with respect tothe contact 70 to deenergize the winding 63. Since the flux generated bythe winding 62 is less than that which effects saturation of the crossbar portions 105 and 106 of the frame 42, said portions becomeunsaturated and flux flow linking the armature 38 is terminated to causedrop out of the latter. The flux generated by the winding 62 is,however, sufllcient to hold the armature 31 in attracted position andthereby the valve 25 in open position.

As the armature 38 drops out, the valve 58 is opened, and the bleed portvalve 36 is closed, so that the chamber 17 becomes pressurized asaforedescribed to cause closure of the high capacity fuel valve 15 Fuelflow to the main burner 12 is now restricted to that which is permittedby the adjustment of the metering screw 29, for example to 20% of therate input of the main burner 12, and a low flame results.

Should the temperature sensed by the bulb 82 continue to rise with thelow flame at the burner 12, the resultant expansion of the volatile fillcauses the contact 77 to move to circuit-interrupting position withrespect to the contact 67 as the control point temperature of thecontact 77 is reached. Circuit-interrupting movement of the contact 77effects deenergization of the winding 62, whereupon the armature 31drops out under the bias of the spring 30 to close the low capacityvalve 25 and shut-off all fuel flow to the main burner 12.

.If, on the other hand, the low flame at the main burner 12 isinsuflicient to maintain the temperature level at 'the bulb 82, and thetemperature thereat drops to the control point of the contact 78, saidcontact moves into and low flame positions in accordance with thedemands of the thermostat 68 as long as the temperature sensed by thebulb 82 does not exceed the control point of the contact 77, and as longas the generator 64 continues to be heated by the flame of the pilotburner. On pilot burner outage, the windings 62 and 63 are deenergizedon cooling of the generator 64 to effect shut-oif of all fuel flow eventhough the thermostat 68 may be calling for heat at the time.

Various changes and modifications may be made in the improved controldevice without departing from the spirit of the invention. For examplethe windings 62 and 63 and their respective controlling contacts mayeach be powered by a separate thermoelectric generator instead of beingconnected in parallel circuit with and powered by the simplethermoelectric generator 64. Also, the pressure regulating meansdisclosed may be omitted where pressure regulation is not desired. Othermodifications of the details of construction shown and described willoccur to those persons skilled in the art; all of such modificationsbeing contemplated as come .within the spirit of the appended claims.

What is claimed as the invention is:

1. An electromagnetic control device for controlling the flow of fuel tofluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, means forcontrolling the flow of fuel to .said reduced capacity fuel outletcomprising a first control member having flow-permitting andflow-preventing positions, means including magnetic members and meansbiasing said magnetic members toward separated relative positions, saidmagnetic members having attracted relative positions providing a lowreluctance flux path, said magnetic members being operatively associatedwith said first flow control member to position the latter inflow-permitting position when said magnetic members are in attractedrelative positions and in flow-preventing position when said members arein separated relative positions, means to establish magnetic flux flowthrough said fiuX path at a first density level sufiicient to hold saidmagnetic members in said attracted relative positions against saidbiasing means and through the same path at a predetermined higherdensity level, said low reluctance flux path means including aportion'having a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, and means for controlling the flow of fuel through said highcapacity f-uel outlet comprising a magnetic second control memberincluding means biasing said second control member toward aflowpreventing position in which it is linked by said shunted flux andmovable against said biasing means toward a flow-permitting position inwhich it is held by said shunted flux when moved thereto.

2. An electromagnetic control device for controlling the flow of fuel tofluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adpted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet having open and closed positions, a second valve for controllingthe flow of fuel to saidhigh capacity fuel outlet, fluid pressureoperated means for actuatingsaid second valve, means including magneticmembers and means biasing said magnetic members toward separatedrelative positions, said magnetic members having attracted relativepositions providing a low reluctance flux path, said magnetic membersbeing operatively associated with said first valve to position thelatter in open position when said magnetic members are in attractedrelative positions and in closed position when said members are inseparated relative positions, means to establish magnetic flux flowthrough said flux path at a first density level suflicient to hold saidmagnetic members in said attracted relative positions against saidbiasing means and through the same path at a predetermined higherdensity level, said low reluctance flux path means including a portionhaving a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, and pilot valve means for controlling said actuating meanscomprising a magnetic control'member and means biasing said magneticcontrol member toward a first position in which it is linked by saidshunted flux and in which it effects disposition of said second valve inclosed position and movable against its said biasing means toward asecond position in which it is held by said shunted flux when movedthereto and in which it effects disposition of said second valve in openposition.

3. An electromagnetic control device for controlling the flow of fuel tofluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet having open and closed positions, a second valve for controllingthe flow of fuel to saidhigh capacity fuel outlet, fluid pressureoperated means for actuating said second valve, means including magneticmembers and means biasing said magnetic members toward separatedrelative positions, said magnetic members having attracted relativepositions providing a low reluctance flux path, said magnetic membersbeing operatively associated With said first valve to position thelatter in open position when said magnetic members are in attractedrelative positions and in closed position when said members are inseparated relative positions, means to establish magnetic flux flowthrough said flux path at a first density level sufficient to hold saidmagnetic members in said attracted relative positions against saidbiasing means and through the same path at a predeterminted higherdensity level, said low reluctance flux path means including a portionhaving a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,Wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, and pilot valve means for controlling said actuating meanscomprising a magnetic control member and means biasing said magneticcontrol member toward a first position in which it is linked by saidshunted flux and in which it effects disposition of said second valve inclosed position and movable against its said biasing means toward asecond position in 'which it is held by said shunted flux when movedthereto and in which it effects disposition of said second valve in openposition, and pressure regulating means in said control body operativelyconnected tosaid second valve for actuation thereby and operable tomaintain the pressure of the fuel in said high capacity meat 9 fueloutlet within predetermined limits in spite'of substantial fluctuationsin the pressure of the fuel in said inlet.

4. An electromagnetic control device, comprising means includingmagnetic members and means biasing said magnetic members towardseparated relative positions, said magnetic members having attractedrelative positions providing a low reluctance flux path, means toestablish magnetic flux flo w through said flux path at a first densitylevel sufiicient to hold said magnetic members in attracted relativepositions against said biasing means and through the same path at apredetermined higher density level, said flux flow at said first densitylevel affording insuificient attractive force to position said magneticmembers in their said attracted relative positions against said biasingmeans, whereas flux flow at said higher density level suflicient to'effect such positioning, said low reluctance flux path means including aportion having a cross-sectional area of a size permitting flux fiowtherethrough at said first density level and saturable by flux fio wtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelpositions said magnetic members in said attracted relative positions,and flux is shunted from said flux path adjacent said saturable portion,and a magnetic control member including means biasing said magneticcontrol member toward a first position in which it is linked by saidshunted flux and movable against said biasing means toward a secondposition in which it is held by said shunted flux when moved thereto.

5. An electromagnetic control device, comprising means includingmagnetic members and means biasing said magnetic members towardseparated relative positions, said magnetic members having attractedrelative positions providing a low reluctance fiuX path, means toestablish magnetic flux flow through said flux path at a first densitylevel sufficient to hold said magnetic members in attracted relativepositions against said biasingmeans and through the same path at apredetermined higher density level, said flux flow at said first densitylevel affording insufficient attractive force to. position said magneticmembers in their said attracted relative positions against said biasingmeans, whereas flux flow at said higher density level is sufficient toeffect such positioning, said low reluctance flux path means including aportion having a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelpositions said magnetic members in said attracted relative positions,and flux is shunted from said flux path adjacent said saturable portion,and a magnetic control member including means biasing said magneticcontrol member toward a first position in which it is linked by saidshunted flux and movable against said biasing means to- Ward a secondposition in which it is held by said shunted flux when moved thereto,and thermostat means comprising first and second contacts in circuitwith said flux flow establishing means for controlling the operation ofthe latter, positioning of said first contact in circuit-making positioneffecting flux flow at said first density level, and positioning of saidsecond contact in circuit-making position While said first contact is incircuit-making position efiecting flux flow at said predetermined higherdensity level, the control point of said second contact being set at apredetermined lower temperature than that of said first contact.

6. An electromagnetic fuel flow controlling device comprising first andsecond valves, means including magnetic members and means biasing saidmagnetic members toward separated relative positions, said magneticmembers having attracted relative positions providing a low reluctanceflux path, said first valve being operatively 10 associated with saidmagnetic members't'obe positioned in closed positionwhen said magneticmembers are in separated relative positions and in open position whensaid magnetic members are in attracted relative positions against saidbiasing means and through the same path at a predetermined higherdensity level, said flux flow at said first density level affordinginsufficient attractive force to position said magnetic members in saidattracted relative positions, whereas flux flow at said higher density,

level is sufiicient to so position said magnetic members and to opensaid first valve, said low reluctance flux path means including aportion having a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses said magnetic members tobe positioned in their attractiverelative positions and flux is shunted from said flux path adjacent saidsaturable portion, and a magnetic control member operatively associatedwith said second valve and including means biasing said magnetic controlmember toward a first position in which it is linked by said shuntedflux and in which it effects closure of said second valve, said magneticcontrol member being movable toward a second position in which iteffects opening of said second valve and in which it is held by saidshunted flux when moved thereto.

7. An electromagnetic control device for controlling the flow of fuel tofluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, means forcontrolling the flow of fuel to said reduced capacity fuel outletcomprising a first control member having flow-permitting andflow-preventing positions, means including magnetic members and meansbiasing said magnetic members toward separated relative positions, saidmagnetic members also having attracted relative positions providing alow reluctance flux path, said magnetic members being operativelyassociated with said first flow controlling member to position thelatter in flow-permitting position when said magnetic members are inattracted relative positions and in flow-preventing position when saidmagnetic members are in separated relative positions, means to establishmagnetic flux flow through said flux path at a first density levelsuificient to hold said magnetic members in their attracted relativepositions against said biasing means and through the same path at apredetermined higher density level, said flux flow at said first densitylevel affording insufficient attractive force to position said mag neticmembers in their said attracted relative positions, Whereas flux flow atsaid higher density level is sufiicient to position said magneticmembers in said attracted relative positions, said low reluctance fluxpath means including a portion having a cross-sectional area of a sizepermitting flux flow therethrough at less than said predetermined higherdensity level, wherefore flux flow through said flux path at said higherdensity level positions said magnetic members in attracted relative positions and thereby said first control member in flow-permitting positionand flux is shunted from said flux path adjacent said saturable portion,and means for controlling the flow of fuel through said high capacityfuel outlet comprising a magnetic second control member and meansbiasing said magnetic second control member toward a flow-preventingposition in which it is linked by said shunted flux and movable againstits biasing means toward a flow-permitting position in which it is heldby said shunted flux when moved thereto, thus affording fuel flow tosaid burner through both outlets for safe ignition, subsequent reductionin the flux flow to said first density level effecting release of saidsecond control member for movement to its flow-preventing position underits biasing means for shut off of the fuel flow through said highcapacity outlet while reduced fuel flow to said burner through saidreduced capacity outlet is permitted by said first control member.

8. An electromagnetic control device for controlling the fiow of fuel tofluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, means forcontrolling the flow of fuel to said reduced capacity fuel outletcomprising a first control member having flow-permitting andflow-preventing positions, means including magnetic members and meansbiasing said magnetic members to separated relative positions, saidmagnetic members having attracted relative positions providing a lowreluctance flux path, said magnetic members being operatively associatedwith said first control member to position the latter in itsflow-permitting position when said magnetic members are in theirattracted relative positions and to position said first control memberin its flow-preventing position when said magnetic members are in theirseperated relative positions, means to establish magnetic flux flowthrough said flux path at a first density level sufi'icient to hold saidmagnetic members in their attracted relative positions against saidbiasing means and through the same path at a predetermined higherdensity level, said flux fiow at said first density level affordinginsufficient attractive force to position said magnetic members in theirattracted relative positions from their separated relative positions,whereas flux flow at said higher density level is sufficient to positionsaid magnetic members in their attracted relative positions from theirseparated relative positions, said low reluctance flux path meansincluding a portion having a cross-sectional area of a size permittingflux flow therethrough at said first density level'and saturable by fluxflow therethrough at less than said predetermined higher density level,wherefore on flux flow through said flux path at said higher densitylevel said magnetic members are positioned in their said attractedrelative positions and thereby said first control member is positionedin its flow-permitting position and flux is shunted from said flux pathadjacent said saturable portion, means for controlling the flow of fuelthrough said high capacity fuel outlet comprising a magnetic secondcontrol member and means biasing the same toward a flow-preventingposition in which it is linked by said shunted fiux, said magneticsecond control member being movable against its said biasing meanstoward a flow-permitting position in which it is held by said shuntedflux when moved thereto, thus affording fuel flow to said burner throughboth outlets for safe ignition, subsequent reduction in the flux flow tosaid first level effecting release of said second control member formovement to its flow-preventing position by its biasing means forshutoff of the fuel flow to said high capacity outlet while reduced fuelflow to said burner through said reduced capacity outlet is permitted bysaid first control member, and thermostat means comprising first andsecond contacts in circuit with said flux flow establishing means forcontrolling the operation of the latter, circuit-making movement of saidfirst contact effecting flux flow at said first density level, andcircuitmaking movement of said second contact while said first contactis in circuit-making position effecting flux flow at said predeterminedhigher density level, the control point of said second contact being setat a predetermined lower temperature level than that of said firstcontact.

9. An electromagnetic control device for controlling the fiow of fuel tofluid burning apparatus having a bumer, comprising a control body havingan inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet, a second valve for controlling the fiow of fuel to said highcapacity outlet, fluid pressure operated means for actuating said secondvalve, means including magnetic members and means biasing said memberstoward separated relative positions, said magnetic members also havingattracted relative positions providing a low reluctance flux path, saidmagnetic members being operatively associated with said first valve toposition the latter in its closed position whenever said magneticmembers are in their attracted relative positions and to position saidfirst valve in open position whenever said magnetic members are in theirseparated relative positions, means to establish magnetic flux flowthrough said flux path at a first density level sufficient to hold saidmagnetic members in their said attracted relative positions against saidbiasing means and through the same path at a predetermined higherdensity level, said flux flow at said first density level affordinginsufficient attractive force to position said magnetic members in theirsaid attracted relative positions from their said separated relativepositions, whereas flux flow at said higher density level is sufiicientto position said magnetic members in their attracted relative positionsand to open said first valve, said low reluctance flux path meansincluding a portion having a cross-sectional area of a size permittingflux fiow therethrough at said first density level and saturable by fluxfiow therethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelpositions said magnetic members in their said attracted relativepositions and thereby said first valve in its said open position andflux is shunted from said flux path adjacent said saturable portion, andpilot valve means for controlling said actuating means comprising amagnetic control member and means biasing the same toward at firstposition in which it is linked by said shunted flux and in which iteffects disposition of said second valve in closed position, saidmagnetic control member being movable against its biasing means toward asecond position in which it is held by said shunted flux and in which iteffects dispostion of said second valve in open position, thus affordingfuel How to said burner through both said outlets for safe ignition,subsequent reduction in the flux flow to said first density leveleffecting release of said control member for movement to its firstposition under its bias and closure of said second valve for shut off ofthe fuel fiow through said high capacity outlet while reduced fuel flowto said burner through said reduced capacity outlet is permitted by saidfirst valve.

10. An electromagnetic control device for controlling the flow of fuelto fluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet, a second valve for controlling the flow of fuel to said highcapacity outlet, fluid pressure operated means for actuating said secondvalve, means including magnetic members and means biasing said memberstoward separated relative positions, said magnetic members also havingattracted relative positions providing a low reluctance fiux path, saidmagnetic members being operatively associated with said first valve toposition the latter in its closed position whenever said magneticmembers are in their attracted relative positions and to position saidfirst valve in open position whenever said magnetic members are in theirseparated relative positions, means to establish magnetic flux flowthrough said flux path at a first density level sufficient to hold saidmagnetic members in their said attracted relative positions against saidbiasing means and through the same path at 13 a predeterminedhigherdensity level, said flux flow at saidfirst density level alfording'insulficient attractive force" to position said magnetic members intheir said attracted relative positions from their said separatedrelativepositions, Whereas flux flow at said higher density level issufiicient to position said magnetic members in their attractedrelativepositions and to open said first valve, said low reluctance flux pathmeans including a portion having a cross-sectional area of a sizepermitting flux flow therethrough at said first density level andsaturable by flux flow therethrough at less than said predeterminedhigher density level, wherefore fiuX flow through saidflux pathatsaidhigher density level positions said magnetic members in their saidattracted relative positions and thereby said first valve in its saidopen position and [flux is shunted from said flux path adjacent saidsaturable portion, and pilot valve means for controlling said actuatingmeans comprisinga magnetic control member and means biasing the sametoward a first position in which it is linked by said shunted flux andin which it effects disposition of said second valve in closed position,said magnetic control member being movable against its biasing meanstoward a second position in which it is held by said shunted fluxand' inwhichit effects disposition of said second valve in open position, thusaffording fuel new to said burner through both said outlets for safeignition, subsequent reduction in the flux flow to said first densitylevel effecting release of said control member for movement to its firstposition under its bias and closure of said second valve for shut ofi ofthe fuel flow through said high capacity outlet while reduced fuel flowto said burner through said reduced capacity outlet is permitted by saidfirst valve, and pressure regulating means in said control bodyoperatively connected to said second valve and cooperable with saidfluid pressure operated actuating means to maintain the pressure of thefuel at said high capacity outlet Within predetermined limits in spiteof substantial fluctuations in the pressure of the fuel at said inlet. V

11. Anelectromagnetic control device, comprising means includingmagnetic members and means biasing said magnetic members towardretracted relative positions, said magnetic members having attractedrelative positions providing a low reluctance flux path, first fluxgenerating means for establishing magnetic flux flow through said fluxpath at a first density level suflicient to hold said moveable membersin their said attracted relative positions against said biasing meansbut insufficient to cause said magnetic members to be positioned intheir attracted relative positions from their said retracted relativepositions, second flux generating means operable with said first fluxgenerating means to establish flux flow through the same path at apredetermined higher density level suificient to position said magneticmembers in their said attractive relative positions from their saidretracted relative positions against said biasing means, said flux pathmeanshaving a portion having a cross-sectional area of a size permittingfiux flow therethrough at said first density level and saturable by fluxflow therethrough at less than said predetermined higher density level,Wherefore flux flow through said flux path at said higher density levelcauses, flux to be shunted from said flux path adjacent said saturableportion, and a magnetic control member including means biasing saidmagnetic control mem ber toward a first position in which it is linkedby said shunted flux and movable against said biasing means to- [Ward asecond position in which it is held by said shunted flux when movedthereto.

12. An electromagnetic control device comprising means includingmagnetic members and means biasing said magnetic members towardretracted relative positions, said magnetic members having attractedrelative positions providing a low reluctance fluxpath, first fluxgenerating means for establishing magnetic flux flow through said fluxpath at a first density levelsuflicient to,

hold said moveable members in their saidiattracted rela-' tive positionsagainst said biasing means but insufficient to position said magneticmembers in their said attracted relative positions from their saidretracted relative positions, second flux generating means operable withsaid first flux generating means to establish flux flow through the samepath at a predetermined higher density level sufficient to position saidmagnetic members in their said attracted relative positions from theirsaid retracted relative positions against said biasing means,thermoelectric genera-tor means connected to energize said first andsecond flux generating means independently, said fiux path means havinga portion having a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, and a magnetic control member including means biasing saidmagnetic control member toward a first position in which it is linked bysaid shunted flux and moveable against its said biasing means toward asecond position in which it is held by said shunted flux when movedthereto.

13. An electromagnetic control device for controlling the flow of fuelto fluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet having open and closed positions, a second valve for controllingthe flow of fuel to said high capacity fuel outlet, means includingmagnetic members and means biasing said magnetic members towardseparated relative poistions, said magnetic members having attractedrelative positions providing a low reluctance flux path, said magneticmembers being operatively associated with said first valve to positionthe latter in open position when said magnetic members are in their saidattracted relative positionsand to closed position when said magneticmembers are in their said separated relative positions, first fluxgenerating means to establish magnetic flux flow through said flux pathat a first density level sufiicient to hold said magnetic members intheir said attracted relative positions against said biasing means butinsufficient to effect positioning of said magnetic members in theirsaid attracted relative positions from their said separated relativepositions, second flux generating means operable with said first fluxgenerating means to establish flux flow through the same path at apredetermined higher density level suflicient to effect positioning ofsaid magnetic members in their said attracted relative positions fromtheir said separated relative positions and hence opening of said firstvalve, said low reluctance flux path means including a portion having across-sectional area of a size permitting fiux flow therethrough at saidfirst density level and saturable by flux flow therethrough at less thansaid predetermined higher density level, wherefore flux flow throughsaid path at said higher density level causes flux to be shunted fromsaid flux path adjacent said saturable portion, and means for actuatingsaid second valve comprising a magnetic control member and means biasingsaid magnetic control member toward a first position in which it islinked by said shunted flux and in which it elfects disposition of saidsecond valve in closed position and movable against its said biasingmeans toward a second position in which it is held by said shunted fluxwhen moved thereto and in which it effects disposition of said secondvalve in open position.

, 14. An electromagnetic control device for controlling the flow of fuelto fluid burning apparatus having a.

burner, comprising a flow control body having an inlet, and a highcapacity fuel outlet adapted to be in communication with said burner,and having a reduced capacity fuel outlet also adapted to be incommunication with said burner, a first valve for controlling the flowof fuel to said reduced capacity fuel outlet having open and closedpositions, a second valve for controlling the flow of fuel to said highcapacity fuel outlet, means including magnetic members and means biasingsaid magnetic members toward separated relative positions, said magneticmembers having attracted relative positions providing a low reluctanceflux path, said magnetic members being operatively associated with saidfirst valve to position the latter in open position when said magneticmembers are in their attracted relative positions and to closed positionwhen said magnetic members are in separated relative positions, firstflux generating means energizable to establish magnetic flux flowthrough said flux path at a first density level sufficient to hold saidmagnetic members in their said attracted relative positions againsttheir said biasing means but insufficient to position said magneticmembers in their said attracted relative positions from their saidseparated relative positions against their said biasing means, secondflux generating means operable when energized with said first fluxgenerating means to establish flux flow through the same path at apredetermined higher density level sulficient to position said magneticmembers in their said attracted relative positions and hence open saidfirst valve, said low reluctance flux path means including a portionhaving a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, means for actuating said second valve comprising a magneticcontrol member and means biasing said magnetic control member toward afirst position in which it is linked by said shunted flux and in whichit effects disposition of said second valve in closed position andmovable against its said bias toward a second position in which it isheld by shunted flux when moved thereto and in which it effectsdisposition of said second valve in open position, and thermostat meanscomprising first and second contacts in circuit with said first andsecond flux generating means respectively for controlling theenergization thereof, circuit-making movement of said first contacteffecting energization of said first flux generating means, andcircuit-making movement of said second contact effecting energization ofsaid second flux generating means, the control point of said secondcontact being set at a predetermined lower temperature than that of saidfirst contact.

15. An electro-magnetic control device for controlling the flow of fuelto fluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel to said reduced capacity fueloutlet having open and closed positions, a second valve for controllingthe flow of fuel to said high capacity fuel outlet, means includingmagnetic members and means biasing said magnetic members towardseparated relative positions, said magnetic members having attractedrelative positions providing a low reluctance flux path, said magneticmembers being operatively associated with said first valve to positionthe latter in open position when said magnetic members are in attractedrelative positions, and to closed positions when said magnetic membersare in separated relative positions, first flux generating means toestablish magnetic flux flow through said flux path at a first densitylevel suificient to position said magnetic members in their saidattracted relative positions against said biasing means but insufficientto effect movement thereof from their said separated relative positionsto their said attracted relative positions, second flux generating'meansoperable with said first flux generating means to establish flux flowthrough the same path at a predetermined higher density level sufiicientto position said magnetic members in their said attracted relativepositions from their said separated relative positions and hence saidfirst valve, said low reluctance flux path means including a portionhaving a cross-sectional area of a size permitting flux flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, and fluid pressure operated means for actuating said secondvalve, and pilot valve means for controlling said actuating meansincluding a magnetic control member and means biasing said magneticcontrol member toward a first position in which it is linked by saidshunted flux and in which it effects disposition of said second valve inclosed position and movable against its biasing means toward a secondposition in which it is held by said shunted flux when moved thereto andin which it effects disposition of said second valve in open position.

16. An electromagnetic control device for controlling the flow of fuelto fluid burning apparatus having a burner, comprising a control bodyhaving an inlet, having a high capacity fuel outlet adapted to be incommunication with said burner, and having a reduced capacity fueloutlet also adapted to be in communication with said burner, a firstvalve for controlling the flow of fuel tosaid reduced capacity fueloutlet having open and closed positions, a second valve for controllingthe flow of fuel to said high capacity fuel outlet, means includingmagnetic members and means biasing said magnetic members towardseparated relative positions, said magnetic members having attractiverelative positions providing a low reluctance flux path, said magneticmembers being operatively associated with said first valve to positionthe latter in open position when said magnetic members are in attractedrelative positions and in closed position when said magnetic members arein separated relative positions, first flux generating means toestablish magnetic flux flow through said flux path at a first densitylevel sufficient to hold said magnetic members in their said attractedrelative positions against said biasing means but insufiicient toposition said magnetic members in their said attracted relativepositions from their said separated relative positions against saidbiasing means, second fiux generating means operable with said firstflux generating means to establish flux flow through the same path at apredetermined higher density level sufficient to change the relativepositions of said magnetic members from their said separated relativepositions to their said attracted relative positions and hence open saidfirst valve, said low reluctance flux path means including a portionhaving a cross-sectional area of a size permitting flux -flowtherethrough at said first density level and saturable by flux flowtherethrough at less than said predetermined higher density level,wherefore flux flow through said flux path at said higher density levelcauses flux to be shunted from said flux path adjacent said saturableportion, fluid pressure operated means for actuating said second valve,and pilot valvemeans controlling said actuating means including amagnetic control member and means biasing said magnetic control membertoward a first position in which it is linked by said shunted flux andin which it effects disposition of said second valve in closed positionand movable against its said biasing means toward a second position inwhich it is held by said shunted flux when moved thereto and in which iteffects disposition of said second valve in open position, and pressureregulating means in said control body operatively connected to saidsecond valve and cooperable with said fluid pressure actuating means tomaintain the pressure at said high capacity outlet within predeterminedlimits in spite of substantial fluctuation in the pressure of the fuelin said inlet.

17. A flow control device for controlling the flow of fluid to fluidfuel burning apparatus comprising high and low capacity valves, anelectromagnetic operator for said valves including permeable core means,first and second flux generating means, and magnetic members and meansrespectively biasing said magnetic members toward retracted relativepositions with respect to said core means, said magnetic members beingoperatively associated individually with said low and high capacity fuelvalves, each of said magnetic members having an attracted position withrespect to said core means in which it elfects opening of its respectivevalve, energization of said first flux generating means causing thelatter to generate suflicient flux in said core means to hold one ofsaid magnetic members in attracted position and said low capacity valvein open position when moved thereto against the respective biasing meansbut insuflicient to efiect attractive movement of either of saidmagnetic members against its said biasing means, energization of saidsecond flux generating means while said first flux generating means isenergized effecting additional flux flow in said core means andactuation of both of said magnetic members to their attracted positionswith respect to said core means and thereby both of said valves towardtheir open positions, energization of said second winding alonegenerating insuificient flux to hold or actuate either of said magneticmembers to their attracted positions, wherefore initiation of fuel flowto said apparatus is always at a high rate for safe ignition since bothvalves are opened substantially simultaneously in response toenergization of both windings, and thereafter said high capacity valvemay be cycled by deenergization and reenergization of the second fluxgenerating means while said low capacity valve is held open byenergization of said first flux generating means, deenergization of saidfirst flux generating means at any time elfecting retraction of saidfirst magnetic member for closure of said low capacity fuel valve andshut 01f of all fuel flow to said apparatus.

References Cited in the file of this patent UNITED STATES PATENTS

